Dynamics of the distribution of invasive alien plants (Asteraceae) in China under climate change

Invasion risk of typical invasive alien plants in mountainous areas and their interrelationship with habitat quality: A case study of Badong County in central China

Invasive alien species (IASs) are a key factor in the loss of regional biodiversity, and exploring the risk of IASs and their interrelationships with biodiversity is of great significance for preventing IASs in a region and enhancing ecological quality. In this study, we used Badong County as an example and analyzed the potential distribution areas of invasive alien plants (IAPs) and habitat quality based on field survey data using models, including the MaxEnt and InVEST models. The results of this research were as follows: (1) The distribution of the four typical IAPs in Badong County was similar, and the high and medium suitability areas were basically distributed in the north-central area of Badong County, which was densely populated and had a low elevation and well-developed river and water systems. (2) The average habitat quality index in Badong County was 0.81, indicating a generally high habitat quality. Spatially, habitat quality in northern townships was significantly lower than that in southern townships. (3) Both the invasion risk of individual IAPs and the comprehensive invasion risk were spatially negatively correlated with habitat quality; areas of high habitat quality and low invasion risk had the largest proportion, followed by areas of low habitat quality and high invasion risk. (4) Competition between species may reduce the negative relationship between the comprehensive IAP invasion risk and habitat quality to a certain extent. The findings of this study can be used to anticipate the prevalence of typical IAPs in Badong County, thereby providing a foundation for preventing and controlling IASs in this region and offering a scientific reference for the study of interrelationships between IASs and biodiversity.

Future climate change facilitates the herb drought-tolerant species distribution than woody species

Drought-tolerant species play a crucial role in maintaining ecosystem services in arid and semi-arid regions wherein subject to rapid climate change. However, how future climate change affect the distribution of drought-tolerant plants with different growth forms (e.g., herb and woody) remains largely unknown. Here, we used the MaxEnt model to simulate the potential species distribution under current conditions, and predicted the future species distribution of 82 common drought-tolerant plants in China under two time periods (2041-2060 and 2081-2100) and three climate change scenarios (SSP126, SSP245 and SSP585) in the future. We found that the western and northern regions of China are hotspots for drought-tolerant plant distribution. Compared with other predictors, aridity index (AI) explained the largest portion of variation (45%) in the distribution patterns of drought-tolerant plant plants. Climate change would change the distribution of drought-tolerant plants, with more than 50% of the species showing a trend of shrinking ranges in China. For both herb and woody plants, the highest turnover values were observed under SSP585 for the period 2081-2100, reaching 37.67% and 29.08%, respectively. Our results highlighted that herb and woody plants respond differently to climate change stresses, with herb plants projected to greatly expand their ranges in the future. These insights are vital for evaluating the impacts of climate change on biodiversity and informing the development of effective adaptation strategies.

Human activities affect the future suitability of alien urban landscape species in China under climate change

Ecologists have paid considerable attention to the adaptation and distribution of urban landscape species in China amid rapid urbanization and climate change, given the essential role of urban species in human activities, urban planning, and sustainable development. However, existing studies primarily concentrate on the effects of climate change on the distribution of native species, creating a research gap regarding alien species. We compiled 5261 distribution data points for 538 alien woody landscape species (WLS) (non-native to China) from 179 cities with populations over one million in China and utilized the MaxEnt model to assess the future distribution and migration patterns of 27 most commonly introduced evergreen broad-leaved, evergreen coniferous, and deciduous broad-leaved species under present, 2041-2060, and 2081-2100 periods according to the Representative Concentration Pathway (RCP) 4.5 and RCP 8.5 climate scenarios. The results indicated that deciduous broad-leaved species were widely distributed in Southwest China, East China, Central China and North China regions, had a broad climate niche and greater adaptability to climate change, while the suitable area of evergreen species were expected to be lower than that of the present stage after 2100. The preserved suitable areas of evergreen species were mainly concentrated in the East China and Central China regions, and the lost suitable areas of evergreen coniferous species were in South China and southern East China regions. We also noted that human activities were the most important factor influencing the species distribution, not only in terms of the differences in suitable areas, but also the spatial diversity patterns. Our study revealed the future distribution patterns of three vegetation types and highlighted the importance of preventing the transformation of alien WLS into invasive species, which can provide valuable guidance for urban planning and development.

Distribution Dynamics of Wide-Ranged and Narrow-Ranged Species From the Pliocene to the Future: Insights From Asian Endemic Holcoglossum (Orchidaceae)

Climate change is an important driver of the potential distribution changes of plants. However, the potential distribution changes of wide-ranged and narrow-ranged species in response to climate change were still controversial. An epiphytic orchid genus Holcoglossum is a key group to address this issue, with about 30% of species widely distributed in the Asian mainland, while the others are only narrowly distributed in special mountains. Combining with species' occurrences, the environmental variables, and Human Footprint data, we analyzed the key predictor variables and predicted the potential distributions and centroid shifts of four wide-ranged and four narrow-ranged Holcoglossum species from the Pliocene to the future using the maximum entropy (MaxEnt) model. Our results showed that the potential distributions of seven Holcoglossum species (except H. subulifolium) were mainly impacted by the precipitation of the warmest quarter in the future. From the Pliocene to the present, the potential distributions of the wide-ranged species (except H. subulifolium) and the narrow-ranged species were contracted. From the present to the future (SSP2-4.5, 2090), the potential distributions of two wide-ranged species (H. flavescens, H. himalaicum) would contract, whereas the other two would expand; the potential distributions of two narrow-ranged species (H. kimballianum, H. wangii) would contract, and the other two would expand. The centroids of three wide-ranged species would migrate southwards (H. amesianum, H. himalaicum, and H. subulifolium), whereas H. flavescens would have nearly no migration; the centroids of three narrow-ranged species would migrate southwards (H. pumilum, H. quasipinifolium, and H. wangii), whereas H. kimballianum would migrate westwards. We found that the vulnerability to climate change of species might be unlinked to their current distribution range and the phylogenetic relationships. This study provides new insights for the potential distribution changes and conservation of narrow-ranged and wide-ranged orchid species.

Modeling current and future distributions of invasive Asteraceae species in Northeast China

The ecological balance and agricultural productivity of northeastern China are seriously threatened by the long-term invasion and spread of Asteraceae plants, which have severely disrupted the region's biodiversity and ecosystem stability. Ambrosia artemisiifolia L., Ambrosia trifida L., and Erigeron canadensis L. are Class 1 malignant invasive species widely distributed across northeastern China. In this context, we selected 36 predictor variables and utilized the MaxEnt model to investigate the influence of current climate on their distribution patterns. Using future climate data, we projected shifts in the distribution dynamics of these three Asteraceae species for two time periods (2041-2060 and 2061-2080) under three climate change scenarios (SSP126, SSP245, and SSP585). The MaxEnt model demonstrated a good predictive impact, with an average area under the curve (AUC) of 0.918. Currently, the three Asteraceae species are primarily found in the southern part of northeastern China. However, due to future climatic changes, their distribution centroids are gradually shifting southwest, leading to an increase in the area of highly suitable zones for these species. Moreover, trend analysis revealed that the potential distribution changes of highly suitable zones for the three Asteraceae species in the southwestern northeastern China are likely to experience an increasing invasive trend under various future climate models. This study provides initial insights into the distribution dynamics of Asteraceae species in northeastern China under climate change, enabling the formulation of plans for managing and preventing the risks and impacts of invasive species.

Predicting Potential Suitable Habitats of Three Rare Wild Magnoliaceae Species (Michelia crassipes, Lirianthe coco, Manglietia insignis) Under Current and Future Climatic Scenarios Based on the Maxent Model

In recent years, the impacts of climate change and human activities have intensified the loss and fragmentation of habitats for wild rare Magnoliaceae. Predicting the potential impacts of future climate change on the suitable habitat distribution of wild and endangered Magnoliaceae species is of great significance for their conservation and application. This study employs the optimized MaxEnt model to investigate current and future potential suitable habitats of three rare Magnoliaceae species (Michelia crassipes, Lirianthe coco, and Manglietia insignis). The dominant environmental variables influencing the distribution of three species were also explored. The results showed the following: (1) The potential habitat range of three Magnoliaceae species currently span from 92-122° N and 19-36° E. Variables associated with temperature (bio2, bio9, bio4) and altitude (Ele) significantly influence the distribution of these species, with precipitation (bio17) and ultraviolet radiation (UVB4) playing a minor role. The warm and humid climate in central and southern China is highly conducive to their growth. (2) Under the SSP126 scenario, after the mid-21st century, the suitable habitat area of Michelia crassipes has undergone a fluctuating trend of initial increase followed by decrease, reducing to 51.84 × 104 km2 in 2090. On the other hand, both the suitable habitat areas of Lirianthe coco and Manglietia insignis show an upward trend. Under the SSP245 and SSP585 scenarios, the total suitable habitat areas of these three rare Magnoliaceae species gradually decrease. (3) We compared the priority protection areas with existing Protected Areas (PAs) in gap analysis; 96.84% of priority conservation areas are lacking effective protection. (4) The distribution centroid is constantly moving to western China. In order to address habitat fragmentation, it is recommended that the range of natural reserves be expanded and ecological corridors be established in the future, preferably according to the predicted suitable climate for protected areas and refuges or habitats for these species. Overall, these findings provide valuable insights for the preservation, stewardship, and utilization of the endangered species of Magnoliaceae under the circumstances of projected global climate change.

Coupling phylogenetic relatedness and distribution patterns provides insights into sandburs invasion risk assessment

Invasive sandburs (Cenchrus spp.), tropical and subtropical plants, are preferred in grasslands and agricultural ecosystems worldwide, causing significant crop production losses and reducing native biodiversity. Integrating phylogenetic relatedness and potentially suitable habitats (PSHs) to identify areas at risk of invasion is critical for prioritizing management efforts and supporting decisions on early warning and surveillance for sandbur invasions. However, despite risk assessments for individual Cenchrus species, the combined analysis of suitable habitats and phylogenetic relationships remains unclear. Therefore, this study aims to assess the invasion risk regions-including PSHs, species richness (SR), and phylogenetic structure-of eight invasive and potentially invasive sandburs in China, to quantify their niche overlap and identify driving factors. Our results showed that the phylogenetic distance of potentially invasive sandburs was closely related to invasive sandburs. Especially, three potentially invasive sandburs, C. ciliaris, C. setigerus, and C. myosuroides, possessed invasion potential resulting from close phylogenetic relatedness and high climatic suitability compared with invasive sandburs. The PSHs for invasive sandburs were distributed in wider regions except northwest China and had higher suitability to different environmental conditions. Potentially invasive sandburs were primarily located in southwestern and southern China driven by precipitation, especially, being inspected in Guangdong, Hainan, and Yunnan on numerous occasions, or potentially introduced in Guangxi, Taiwan, and Fujian for sandburs invasion hotspots. The phylogenetic clustering for eight sandburs occurred in the eastern, center, and southern coastal China, where higher SR in distribution was correlated with invasion hotspots. The SR and phylogenetic relatedness metrics were related to temperature and topographic variables. Totally, the expansion and invasion risk could be increased toward higher latitudes under future global warming. These findings offer novel insights for the prevention and management of sandburs invasions.

Distribution and Conservation of Ephedra rhytidosperma

With global warming and increasingly intensified human activities, numerous species are on the verge of extinction, ca. 28% of living species are threatened globally, although conservation of endangered species has received worldwide attention. It remains unclear if threatened species have been appropriately conserved or not. Ephedra rhytidosperma is an endangered species and included in the List of National Key Protected Wild Plants in China (released in September 2021). This shrubby species is endemic to the Helan Mountains in northwestern China where it dominates the lowland vegetation. We have conducted an integrative investigation on the conservation of the species. We used the MaxEnt model to predict the potential geographic distribution of E. rhytidosperma under past, current, and future climatic scenarios based on distributional occurrences and environmental data and investigated the conservation status and its effectiveness. The results show that E. rhytidosperma is mainly distributed in lowland Helan Mountains, while the range in the past and future show different patterns. The range has shrunk significantly and migrated westwards since the Last Interglacial, whereas the projected area in the future displays a fluctuating pattern and easterly migration. The precipitation (Bio14), the temperature (Bio9), and degree of slope (Slope) are the dominant factors influencing its current and future ranges. We also found that E. rhytidosperma populations at different altitudes showed different adaptations to the environment. Our assessment of the conservation status of the hotspots revealed that only 15.1% occur in nature reserves, implying that a large conservation gap remains. In addition, there has been less attention paid to ex situ conservation. As a result, we propose conducting an integrative conservation approach including both in situ and ex situ management to save E. rhytidosperma. Our study lays a solid foundation for the development of targeted conservation strategies for E. rhytidosperma.

Ensemble modeling of aquatic plant invasions and economic cost analysis in China under climate change scenarios

Pistia stratiotes, Eichhornia crassipes, Alternanthera philoxeroides, and Cabomba caroliniana are officially recognized as invasive aquatic plants in China. Accurately predicting their invasion dynamics under climate change is crucial for the future safety of aquatic ecosystems. Compared to single prediction models, ensemble models that integrate multiple algorithms provide more accurate forecasts. However, there has been a notable lack of research utilizing ensemble models to collectively predict the invasive regions of these four species in China. To address this gap, we collected and analyzed comprehensive data on species distribution, climate, altitude, population density, and the normalized difference vegetation index to accurately predict the future invasive regions and potential warnings for aquatic systems concerning these species. Our results indicate that suitable areas for invasive aquatic plants in China are primarily located in the southeastern region. Significant differences exist in the suitable habitats for each species: P. stratiotes and E. crassipes have broad distribution areas, covering most water systems in southeastern China, while C. caroliniana is concentrated in the middle and lower reaches of the Yangtze River and the estuaries of the Yangtze and Pearl Rivers. A. philoxeroides has an extensive invasion area, with the North China Plain projected to become a suitable invasion region in the future. The main factors influencing future invasions are human activities and climate change. In addition, under climate change, the suitable habitats for these invasive aquatic plants are expected to expand towards higher latitudes. We also estimated the economic costs associated with invasive aquatic plants in China using the Invacost database, revealing cumulative costs of US$5525.17 million, where damage costs (89.70%) significantly exceed management costs (10.30%). Our innovative approach, employing various ensemble algorithms and water system invasion forecasts, aims to effectively mitigate the future invasions and economic impacts of these species.

Assessing the climatic niche changes and global invasion risk of Solanum elaeagnifolium in relation to human activities

As an invasive plant, Solanum elaeagnifolium has posed a serious threat to agriculture and natural ecosystems worldwide. In order to better manage and limit its spread, we established niche models by combining distribution information and climate data from the native and invasive ranges of S. elaeagnifolium to analyze its niche changes during its colonization. Additionally, we evaluated its global invasion risk. Our results showed that the distribution of S. elaeagnifolium is affected by temperature, precipitation, altitude, and human activities. Solanum elaeagnifolium exhibits different degrees of niche conservatism and niche shift in different invasion ranges. During the global invasion of S. elaeagnifolium, both the niche shift and conservatism were observed, however, niche shift was particularly significant due to the presence of unoccupied niches (niche unfilling). Solanum elaeagnifolium generally occupied a relatively stable niche. However, a notable expansion was observed primarily in Europe and China. In Australia and Africa, its niche largely remains a subset of its native niche. Compared to the niche observed in its native range, its realized niche in China and Europe has shifted toward lower temperature and higher precipitation levels. Conversely, in Africa, the niche has shifted toward lower precipitation levels, while in Australia, it has shifted toward higher temperature. Our model predicted that S. elaeagnifolium has high invasion potential in many countries and regions. The populations of S. elaeagnifolium in China and Africa have reached the adapted stage, while the populations in Australia and Europe are currently in the stabilization stage. In addition, our research suggests that the potential distribution of S. elaeagnifolium will expand further in the future as the climate warms. All in all, our study suggests that S. elaeagnifolium has high potential to invade globally. Due to its high invasive potential, global surveillance and preventive measures are necessary to address its spread.

Spatiotemporal distribution prediction of the relict and endangered plant Tetraena mongolica in inner Mongolia, China under climate change

Climate change significantly affects the distribution of plant species, particularly that of relict plants. Tetraena mongolica Maxim. is a first-class endangered relict plant in China, primarily found in Inner Mongolia. This study explored the impact of multiple factors on its potential distribution under climate change. Considering a comprehensive set of 42 potential influencing variables, including climate, soil, net primary productivity (NPP), human activities, and topography, 29 variables were selected. The maximum entropy (MaxEnt) model was used to construct separate climate and soil niche models, and an "overlay function" was employed to construct a dual-suitability model. By establishing five different scenarios, we analyzed the effects of climate, human activities, and NPP on T. mongolica distribution. The results showed that climate is the most significant factor, soil constraints limit its distribution, and human activities reduce its suitable habitats. Although the direct influence of NPP is limited, it may indirectly affect T. mongolica distribution by improving habitat conditions. Future climate change is expected to sharply reduce suitable habitat areas, with the center of distribution migrating eastward. The study's findings imply that climate change, human activities, and soil conditions significantly impact the distribution and survival of the endangered plant T. mongolica, necessitating comprehensive conservation measures to mitigate habitat loss and ensure its preservation.

Predicting the Impact of Climate Change on Corylus Species Distribution in China: Integrating Climatic, Topographic, and Anthropogenic Factors

This study investigates the impact of climate change on the distribution of Corylus species in China using the MaxEnt model. Key environmental variables, such as Bio6 (mean temperature of the coldest month) and human footprint, emerged as significant determinants of habitat suitability. The study reveals substantial shifts in suitable habitats due to global warming and increased precipitation, with notable expansion towards higher latitudes. Species like Corylus heterophylla Fisch. ex Bess. and Corylus mandshurica Maxim. demonstrate resilience in extreme conditions, highlighting the importance of specific ecological traits for conservation. Future projections under various SSP scenarios predict continued habitat expansion, emphasizing the need for targeted conservation strategies to address the critical role of human activities. This research highlights the complex interplay between climatic, topographic, and anthropogenic factors in shaping Corylus habitats, advocating for integrated adaptive management approaches to ensure their sustainability amid ongoing climate change.

Reconstructing the biological invasion of noxious invasive weed Parthenium hysterophorus and invasion risk assessment in China

Invasive alien plants (IAPs) present a severe threat to native ecosystems and biodiversity. Comprehending the potential distribution patterns of these plant invaders and their responses to climate change is essential. Parthenium hysterophorus, native to the Americas, has become an aggressively invasive species since its introduction to China in the 1930s. This study aims to collect and reconstruct the historical occurrence and invasion of P. hysterophorus. Using the optimal MaxEnt model, the potential geographical distributions of P. hysterophorus were predicted based on screened species occurrences and environmental variables under the current and three future scenarios in the 2030s, 2050s, and 2070s (i.e., SSP1-2.6, SSP2-4.5, and SSP5-8.5), and the invasion risk of P. hysterophorus in Chinese cities, croplands, forests, and grasslands was assessed. The results show that: (1) The species initially invaded highly suitable areas and further spread to regions with non-analogous climate conditions. (2) Under the current climatic conditions, the overall potential distribution of P. hysterophorus is characterized by more in the southeast and less in the northwest. Climate variables, including mean annual temperature (bio1), precipitation in the wettest month (bio13), isothermality (bio3), and temperature seasonality (bio4), are the primary factors influencing its distribution. (3) The potential distribution of P. hysterophorus will expand further under future climate scenarios, particularly toward higher latitudes. (4) Forests and crop lands are the areas with the most serious potential invasion risk of P. hysterophorus. Therefore, we suggest that the government should strengthen the monitoring and management of P. hysterophorus to prevent its spread and protect agro-ecosystems and human habitats. Depending on the potential risk areas, measures such as quarantine, removal, and publicity should be taken to mitigate the threat of P. hysterophorus invasion and to raise awareness of P. hysterophorus invasion prevention.

Contrasting range changes and drivers of four forest foundation species under future climate change in China

Forest foundation species, vital for shaping community structure and dynamics through non-trophic level interactions, are key to forest succession and sustainability. Despite their ecological importance, the habitat ranges of these species in China and their responses to future climate change remain unclear. Our study employed the optimal MaxEnt model to assess the range shifts and their essential drivers of four typical forest foundation species from three climatic zones in China under climate scenarios, including Acer tegmentosum, Acer pseudo-sieboldianum (temperate zone), Quercus glandulifera (subtropical zone), and Ficus hispida (tropical zone). The optimal MaxEnt model exhibited high evaluation indices (AUC values > 0.90) for the four foundation species, indicating excellent predictive performance. Currently, we observed that A. tegmentosum and A. pseudo-sieboldianum are predominantly inhabited temperate forest areas in northeastern China, Q. glandulifera is primarily concentrated in subtropical forests in southeastern China, and F. hispida is mainly distributed across the tropical forests in southern China. Climate factors, particularly temperature, emerged as the primary environmental factors influencing the potential range of forest foundation species. Moreover, precipitation strongly influenced the potential range of A. tegmentosum and A. pseudo-sieboldianum, while elevation exhibited a greater impact on the range of Q. glandulifera and F. hispida. Under future climate scenarios, suitable areas for A. tegmentosum and A. pseudo-sieboldianum tend to expand southward, F. hispida tends to expand northward, while Q. glandulifera exhibited a tendency to contract towards the center. This study advances our understanding of the spatial and temporal dynamics of forest foundation species in China under climate change, providing critical insights for conservation efforts and sustainable forest management practices.

Modeling the distribution of pine wilt disease in China using the ensemble models MaxEnt and CLIMEX

Pine wilt disease (PWD) is a devastating plant disease caused by the pinewood nematode (PWN, Bursaphelenchus xylophilus) that is transmitted by several beetle species in the genus, Monochamus. Once present, the disease is difficult to control. Prevention rather than control is regarded as an effective strategy for PWD management. Central to this prevention strategy is the ability to predict the potential distribution of the disease. Here, we employed an integrated MaxEnt and CLIMEX approach to model the potential distribution of PWD under various climate-change scenarios. Our results indicate that rising temperatures and lower humidity under climate change will render some of the northern regions of China more suitable for the nematode and these beetles, causing the gradual northward movement of PWD. Furthermore, suitable habitats for three pine species, Pinus massoniana, P. taiwanensis and P. shurbergia, overlap with PWN and Monochamus, suggesting that these three species are potentially at high risk of PWD. Thus, PWD management should target the northern regions of China and the three pine species that are most susceptible to PWD.

Changing effects of energy and water on the richness distribution pattern of the Quercus genus in China

Climate varies along geographic gradients, causing spatial variations in the effects of energy and water on species richness and the explanatory power of different climatic factors. Species of the Quercus genus are important tree species in China with high ecological and socioeconomic value. To detect whether the effects of energy and water on species richness change along climatic gradients, this study built geographically weighted regression models based on species richness and climatic data. Variation partition analysis and hierarchical partitioning analysis were used to further explore the main climatic factors shaping the richness distribution pattern of Quercus in China. The results showed that Quercus species were mainly distributed in mountainous areas of southwestern China. Both energy and water were associated with species richness, with global slopes of 0.17 and 0.14, respectively. The effects of energy and water on species richness gradually increased as energy and water in the environment decreased. The interaction between energy and water altered the effect of energy, and in arid regions, the effects of energy and water were relatively stronger. Moreover, energy explained more variation in species richness in both the entire study area (11.5%) and different climate regions (up to 19.4%). The min temperature of coldest month was the main climatic variable forming the richness distribution pattern of Quercus in China. In conclusion, cold and drought are the critical climatic factors limiting the species richness of Quercus, and climate warming will have a greater impact in arid regions. These findings are important for understanding the biogeographic characteristics of Quercus and conserving biodiversity in China.